Rapid Access to Tigliane, Ingenane, and Rhamnofolane Diterpenes from a Lathyrane Precursor via Biomimetic Skeleton Transformation Strategy

Bioinspired skeleton transformation of a tricyclic lathyrane-type Euphorbia diterpene was conducted to efficiently construct
a tetracyclic tigliane diterpene on a gram scale via a key aldol condensation.
The tigliane diterpene was then respectively converted into naturally
rare ingenane and rhamnofolane diterpenes through a semipinacol rearrangement
and a visible-light-promoted regioselective cyclopropane ring-opening
reaction. This work provides a concise strategy for high-efficiency
access to diverse polycyclic Euphorbia diterpene
skeletons from abundant lathyrane-type natural products and paves
the way for biological activity investigation of naturally rare molecules.